196 multiplication or division facts

[Airehead]

A ten-year old boy answered 196 math facts in one minute to gain the Guinness title.  This video shows him in action.

I don't care who you are-- that is fast.

 

[Randomguy]

Damn!

[donkpow]

14 minutes ago, Airehead said:

A ten-year old boy answered 196 math facts in one minute to gain the Guinness title.  This video shows him in action.

I don't care who you are-- that is fast.

 

And yet the video still ran over a minute.

[Bikeguy]

5 minutes ago, donkpow said:

And yet the video still ran over a minute.

The test didn't start until 0:04 and the test ended 1 minute later.  Plus the scoring = 1:15

23 minutes ago, Airehead said:

I don't care who you are-- that is fast.

OMG I could NEVER type that fast, let alone answer the 196 questions too.  That was incredibly fast.  

[jsharr ★]

I could get at least 10 of those in a minute.  Probably more.  Maybe.

[Forum Administrator]

I am a 45 year old with multiple degrees. I still have to stop and think about my multiplication facts when it comes to sevens.   If you ask me what 7x4 is, I have to do 7x2 is 14, 14x2 is 28, therefore, 7x4 = 28.

You know what's worse than that?  I double checked 7x4 on a calculator just to confirm that I was correct.

[Airehead]

18 minutes ago, Forum Administrator said:

I am a 45 year old with multiple degrees. I still have to stop and think about my multiplication facts when it comes to sevens.   If you ask me what 7x4 is, I have to do 7x2 is 14, 14x2 is 28, therefore, 7x4 = 28.

You know what's worse than that?  I double checked 7x4 on a calculator just to confirm that I was correct.

me too and sometimes I have to use the finger trick to do 9x8

[Kirby]

I couldn't do that even if you asked me the same math fact 165 times.

[MickinMD ★]

I wonder how much he knows about the old math tricks that people used to use before calculators became big at the end of the 60's.

I used to know some of them.

When multiplying any two digit number by 11, the answer is the first digit of the number, followed by the two digits of the number added together, followed by the second digit.  So 52 x 11 = 5, 5+2, 2 or 572.  If the sum is greater than 9, carry the "10" to the first digit of the answer: 87 x 11 = 8, 8+7, 7 = 957.

I still use the simplification tricks when I divide supermarket receipts into groceries, beverages, and snacks categories for my budget spreadsheet.

For example $19.99 x 5 is just 5 cents less than $20 x 5, or $99.95.

There's one key thing you have to avoid, though in dividing.

I used to stump my gifted and talented physics students with this one:

given a = 1, b = 1

a^2 = a^2

b^2 = ab

Subtracting the 2nd equation from the 1st:

a^2 - b^2 = a^2 - ab

Since the difference of two squares is (a+b)(a-b) and factoring a out of the right side:

(a+b)(a-b) = a(a-b)

Canceling a-b from each side:

a + b = a

Or:

1 + 1 = 1 so 2 = 1

This would blow the gifted kids away.  What principle of math did I violate?

[maddmaxx ★]

I can count from 0 to 100 very quickly.

0

1

10

11

100

[donkpow]

1 hour ago, MickinMD said:

What principle of math did I violate?

That one would use math after graduating high school.